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	$148.69	3.208%	$153.46	$153.46	$153.45	$153.50
Purchase #2	$6.37	12.165%	$7.1449	$7.14	$7.15	$7.10
Purchase #3	$28.28	13.438%	$32.0803	$32.08	$32.10	$32.10
Purchase #4	$232.87	6.630%	$248.3093	$248.31	$248.30	$248.30
Purchase #5	$165.89	5.669%	$175.2943	$175.29	$175.30	$175.30
Purchase #6	$148.56	13.512%	$168.6334	$168.63	$168.65	$168.60
Purchase #7	$99.96	9.138%	$109.0943	$109.09	$109.10	$109.10
7 purchase totals =	$830.62		$894.0165	$894.00	$894.05	$894.00