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	$152.47	4.454%	$159.261	$159.26	$159.25	$159.30
Purchase #2	$156.67	5.384%	$165.1051	$165.11	$165.10	$165.10
Purchase #3	$33.25	5.343%	$35.0265	$35.03	$35.05	$35.00
Purchase #4	$95.30	6.616%	$101.605	$101.61	$101.60	$101.60
Purchase #5	$160.40	7.606%	$172.6	$172.60	$172.60	$172.60
Purchase #6	$192.57	4.173%	$200.6059	$200.61	$200.60	$200.60
Purchase #7	$159.88	12.768%	$180.2935	$180.29	$180.30	$180.30
7 purchase totals =	$950.54		$1,014.4970	$1,014.51	$1,014.50	$1,014.50