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	$177.47	11.608%	$198.0707	$198.07	$198.05	$198.10
Purchase #2	$75.36	5.848%	$79.7671	$79.77	$79.75	$79.80
Purchase #3	$152.61	8.390%	$165.414	$165.41	$165.40	$165.40
Purchase #4	$81.73	10.676%	$90.4555	$90.46	$90.45	$90.50
Purchase #5	$142.27	3.701%	$147.5354	$147.54	$147.55	$147.50
Purchase #6	$56.89	10.318%	$62.7599	$62.76	$62.75	$62.80
Purchase #7	$235.39	11.208%	$261.7725	$261.77	$261.75	$261.80
7 purchase totals =	$921.72		$1,005.7751	$1,005.78	$1,005.70	$1,005.90