Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$146.95	4.436%	$153.4687	$153.47	$153.45	$153.50
Purchase #2	$195.64	8.765%	$212.7878	$212.79	$212.80	$212.80
Purchase #3	$110.39	3.318%	$114.0527	$114.05	$114.05	$114.10
Purchase #4	$115.66	3.259%	$119.4294	$119.43	$119.45	$119.40
Purchase #5	$238.67	10.740%	$264.3032	$264.30	$264.30	$264.30
Purchase #6	$80.28	4.502%	$83.8942	$83.89	$83.90	$83.90
Purchase #7	$203.27	5.711%	$214.8787	$214.88	$214.90	$214.90
7 purchase totals =	$1,090.86		$1,162.8147	$1,162.81	$1,162.85	$1,162.90