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	$98.42	13.468%	$111.6752	$111.68	$111.70	$111.70
Purchase #2	$114.57	3.691%	$118.7988	$118.80	$118.80	$118.80
Purchase #3	$219.61	6.225%	$233.2807	$233.28	$233.30	$233.30
Purchase #4	$215.32	12.530%	$242.2996	$242.30	$242.30	$242.30
Purchase #5	$44.59	6.604%	$47.5347	$47.53	$47.55	$47.50
Purchase #6	$173.65	11.506%	$193.6302	$193.63	$193.65	$193.60
Purchase #7	$73.36	6.399%	$78.0543	$78.05	$78.05	$78.10
7 purchase totals =	$939.52		$1,025.2735	$1,025.27	$1,025.35	$1,025.30