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	$141.48	7.803%	$152.5197	$152.52	$152.50	$152.50
Purchase #2	$36.72	12.128%	$41.1734	$41.17	$41.15	$41.20
Purchase #3	$61.28	6.865%	$65.4869	$65.49	$65.50	$65.50
Purchase #4	$147.33	5.473%	$155.3934	$155.39	$155.40	$155.40
Purchase #5	$143.46	3.631%	$148.669	$148.67	$148.65	$148.70
Purchase #6	$193.77	3.681%	$200.9027	$200.90	$200.90	$200.90
Purchase #7	$160.39	5.352%	$168.9741	$168.97	$168.95	$169.00
7 purchase totals =	$884.43		$933.1192	$933.11	$933.05	$933.20