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	$105.50	5.182%	$110.967	$110.97	$110.95	$111.00
Purchase #2	$61.67	10.740%	$68.2934	$68.29	$68.30	$68.30
Purchase #3	$58.90	4.188%	$61.3667	$61.37	$61.35	$61.40
Purchase #4	$144.37	12.498%	$162.4134	$162.41	$162.40	$162.40
Purchase #5	$55.90	7.795%	$60.2574	$60.26	$60.25	$60.30
Purchase #6	$94.64	5.216%	$99.5764	$99.58	$99.60	$99.60
Purchase #7	$158.47	4.391%	$165.4284	$165.43	$165.45	$165.40
7 purchase totals =	$679.45		$728.3027	$728.31	$728.30	$728.40