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	$153.97	9.820%	$169.0899	$169.09	$169.10	$169.10
Purchase #2	$122.80	9.190%	$134.0853	$134.09	$134.10	$134.10
Purchase #3	$89.59	3.745%	$92.9451	$92.95	$92.95	$92.90
Purchase #4	$121.72	4.597%	$127.3155	$127.32	$127.30	$127.30
Purchase #5	$195.45	4.171%	$203.6022	$203.60	$203.60	$203.60
Purchase #6	$88.96	13.362%	$100.8468	$100.85	$100.85	$100.80
Purchase #7	$202.69	8.362%	$219.6389	$219.64	$219.65	$219.60
7 purchase totals =	$975.18		$1,047.5237	$1,047.54	$1,047.55	$1,047.40