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	$188.79	4.223%	$196.7626	$196.76	$196.75	$196.80
Purchase #2	$191.25	10.608%	$211.5378	$211.54	$211.55	$211.50
Purchase #3	$11.31	10.674%	$12.5172	$12.52	$12.50	$12.50
Purchase #4	$61.46	10.719%	$68.0479	$68.05	$68.05	$68.00
Purchase #5	$94.69	4.282%	$98.7446	$98.74	$98.75	$98.70
Purchase #6	$144.42	4.282%	$150.6041	$150.60	$150.60	$150.60
Purchase #7	$172.30	10.678%	$190.6982	$190.70	$190.70	$190.70
7 purchase totals =	$864.22		$928.9124	$928.91	$928.90	$928.80