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	$174.86	5.843%	$185.0771	$185.08	$185.10	$185.10
Purchase #2	$6.50	6.406%	$6.9164	$6.92	$6.90	$6.90
Purchase #3	$28.95	6.502%	$30.8323	$30.83	$30.85	$30.80
Purchase #4	$85.28	4.535%	$89.1474	$89.15	$89.15	$89.10
Purchase #5	$99.67	6.870%	$106.5173	$106.52	$106.50	$106.50
Purchase #6	$51.57	12.190%	$57.8564	$57.86	$57.85	$57.90
Purchase #7	$141.71	5.431%	$149.4063	$149.41	$149.40	$149.40
7 purchase totals =	$588.54		$625.7532	$625.77	$625.75	$625.70