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	$161.78	7.673%	$174.1934	$174.19	$174.20	$174.20
Purchase #2	$145.26	8.790%	$158.0284	$158.03	$158.05	$158.00
Purchase #3	$220.90	10.856%	$244.8809	$244.88	$244.90	$244.90
Purchase #4	$86.64	4.432%	$90.4799	$90.48	$90.50	$90.50
Purchase #5	$80.32	10.369%	$88.6484	$88.65	$88.65	$88.60
Purchase #6	$31.47	5.250%	$33.1222	$33.12	$33.10	$33.10
Purchase #7	$217.73	7.562%	$234.1947	$234.19	$234.20	$234.20
7 purchase totals =	$944.10		$1,023.5479	$1,023.54	$1,023.60	$1,023.50