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	$190.85	11.456%	$212.7138	$212.71	$212.70	$212.70
Purchase #2	$59.55	11.368%	$66.3196	$66.32	$66.30	$66.30
Purchase #3	$188.97	4.127%	$196.7688	$196.77	$196.75	$196.80
Purchase #4	$54.96	5.373%	$57.913	$57.91	$57.90	$57.90
Purchase #5	$240.40	11.428%	$267.8729	$267.87	$267.85	$267.90
Purchase #6	$189.90	10.369%	$209.5907	$209.59	$209.60	$209.60
Purchase #7	$91.52	5.736%	$96.7696	$96.77	$96.75	$96.80
7 purchase totals =	$1,016.15		$1,107.9484	$1,107.94	$1,107.85	$1,108.00