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	$237.57	10.481%	$262.4697	$262.47	$262.45	$262.50
Purchase #2	$229.31	4.774%	$240.2573	$240.26	$240.25	$240.30
Purchase #3	$248.46	10.187%	$273.7706	$273.77	$273.75	$273.80
Purchase #4	$45.59	10.454%	$50.356	$50.36	$50.35	$50.40
Purchase #5	$29.48	7.113%	$31.5769	$31.58	$31.60	$31.60
Purchase #6	$159.31	7.632%	$171.4685	$171.47	$171.45	$171.50
Purchase #7	$92.26	4.518%	$96.4283	$96.43	$96.45	$96.40
7 purchase totals =	$1,041.98		$1,126.3273	$1,126.34	$1,126.30	$1,126.50