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	$94.32	10.110%	$103.8558	$103.86	$103.85	$103.90
Purchase #2	$133.90	9.574%	$146.7196	$146.72	$146.70	$146.70
Purchase #3	$156.41	6.223%	$166.1434	$166.14	$166.15	$166.10
Purchase #4	$194.51	3.317%	$200.9619	$200.96	$200.95	$201.00
Purchase #5	$188.48	6.849%	$201.389	$201.39	$201.40	$201.40
Purchase #6	$185.82	7.791%	$200.2972	$200.30	$200.30	$200.30
Purchase #7	$99.31	9.298%	$108.5438	$108.54	$108.55	$108.50
7 purchase totals =	$1,052.75		$1,127.9107	$1,127.91	$1,127.90	$1,127.90