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	$33.28	5.325%	$35.0522	$35.05	$35.05	$35.10
Purchase #2	$108.45	13.812%	$123.4291	$123.43	$123.45	$123.40
Purchase #3	$32.41	13.828%	$36.8917	$36.89	$36.90	$36.90
Purchase #4	$20.45	10.782%	$22.6549	$22.65	$22.65	$22.70
Purchase #5	$181.63	6.361%	$193.1835	$193.18	$193.20	$193.20
Purchase #6	$186.75	5.233%	$196.5226	$196.52	$196.50	$196.50
Purchase #7	$96.41	4.132%	$100.3937	$100.39	$100.40	$100.40
7 purchase totals =	$659.38		$708.1277	$708.11	$708.15	$708.20